#!/usr/bin/env python3


def solve(S: str):
    if S >= 30:
        return "Yes"
    return "No"


def main():
    S = int(input())
    answer = solve(S)
    print(answer)


if __name__ == "__main__":
    main() def solve(S: str):
    if S >= 30:
        return "Yes"
    return "No" solve if S >= 30:
        return "Yes"
     S >= 30 S 30 return "Yes" "Yes" return "No" "No" S: str S def main():
    S = int(input())
    answer = solve(S)
    print(answer) main S = int(input()) S int(input()) int input() input answer = solve(S) answer solve(S) solve S print(answer) print answer if __name__ == "__main__":
    main() __name__ == "__main__" __name__ "__main__" main() main def main():
    S = int(input())
    answer = solve(S)
    print(answer) def main():
    S = int(input())
    answer = solve(S)
    print(answer) main def solve(S: str):
    if S >= 30:
        return "Yes"
    return "No" def solve(S: str):
    if S >= 30:
        return "Yes"
    return "No" solve
#!/usr/bin/env python3


def solve(S: str):
    if S >= 30:
        return "Yes"
    return "No"


def main():
    S = int(input())
    answer = solve(S)
    print(answer)


if __name__ == "__main__":
    main()
